A test pins which finished runs the feed folds as quiet: nothing pushed, opened or said in the run's window, and never a run the record cannot find #6701

src/feed/quiet.ts decides which runs leave the timeline for the "N quiet runs" line. If it is wrong, a run that did something disappears from the feed. No test names quietRunEventIds.

Done when test/feed-quiet.test.ts shows:

• [ ] A finished ok run whose agent wrote nothing in its window is quiet.
• [ ] The same run with a push to the repository, a push to the agent's fork, a pull, a comment, or an issue in its window is not quiet, one case for each.
• [ ] A failed run, and a run.finished event whose run row is gone, are never quiet.
• [ ] Something the agent wrote just outside the window does not stop the run being quiet.

Files: test/feed-quiet.test.ts, src/feed/quiet.ts